City life requires a lot of attention. Navigating a busy sidewalk while processing loud storefronts and avoiding rogue pigeons may feel like second-nature at times, but it's actually quite a bit of work for the human brain.

Psychologists do know that quick walks through the park can restore our focus, but they're still getting a handle on just what urbanization means for human cognition.

A new series of behavioral studies offers some of the richest evidence to date on the mental exhaustion of urban living. In an upcoming issue of the Journal of Experimental Psychology: Human Perception and Performance, a group of British psychologists reports that people who live in cities show diminished powers of general attention compared to people from remote areas. With so much going on around them, urbanites don't pay much attention to surroundings unless they're highly engaging.

Instead, as the researchers put it, city dwellers have developed a form of attention that puts priority on "the search for potential dangers or new opportunities":

While reduced attentional engagement may be advantageous in high-demanding urban scenarios, it comes at the cost of a generally reduced level of attentional selectivity.

The research team from Goldsmiths' College, part of the University of London system, conducted their studies with a unique population: the Himba people of Namibia. Some Himba remain traditional cattle herders, while others now lead a "largely Western existence" in the nearby town of Opuwo. The scenario created a rare opportunity to examine the urban-rural psychological divide in raw form.

(To be sure their findings had broader relevance, the researchers also ran some tests with Londoners and found the two types of urban brains to be similar.)

In one experiment, the researchers gave the Himba a basic spatial attention task. The study participants identified a target (in this case, arrows pointing a certain way) on a visual screen filled with other distractors (arrows pointing other ways). The traditional Himba, living in remote regions, showed more focused attention during the task than the city Himba did. The poor performance held for all urbanites — those born in the city as well as those who'd moved there later in life.

In a second test, the researchers found they could overload the brains of rural Himba so they'd perform like urban Himba. This time test participants repeated the spatial task but also had to juggle a working memory task (e.g. remembering several numbers) in between trials. With this additional distraction on their minds (known as "cognitive load"), rural Himba had the same reduced focus that city Himba had shown in the initial experiment.

"Indeed, the effect of cognitive load was indistinguishable from the effect of urbanization," the researchers report.

After a few more experiments the researchers formulated a theory about what's happening here. They don't think city life actually depletes one's powers of attention. (That's because, on one test of straight working memory, city Himba scored higher than rural Himba.) Instead, they suspect that city attention only becomes engaged when people cross paths with something especially worthy of notice. (On other tests, city Himba did show the same focus as rural Himba when they looked at highly engaging stimuli, like faces.)

So a quick summary, for those readers on the verge of losing focus: the brains of people in remote places seem ready to focus on the task at hand, while the brains of their urban counterparts seem prepared to explore the ever-changing conditions of city life. Certainly explains why some country folk find the city overwhelming, and some city folk find the country a little dull. Nothing personal — strictly neural.